Date of Award
6-1-1991
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Biochemistry and Molecular Biology
Abstract
Phosphoenolpyruvate carboxykinase (PEPCK), an enzyme which exists as two distinct isozymes, is distributed in a species- and tissue-specific manner. The purpose of this study was to systematically determine the quantity and intracellular location of both isozyme activities of PEPCK in a number of major and important tissues of several species of mammals and birds.Both the intracellular distribution and quantities of both PEPCK isozyme activities were determined in liver, kidney, gastrointestinal mucosa, and adipose tissue; and the total quantity of the enzyme activity was determined in skeletal muscle, brain, spleen, lung, and heart of fed rat and fed and fasted rabbit, guinea pig, chicken, and pigeon.Liver and kidney of all five species as well as the gastrointestinal mucosa of rabbit contain very large amounts of PEPCK activity per gram tissue. Brown adipose tissue of rat also contains a substantial amount of PEPCK activity per gram tissue. Skeletal muscle of all five species consistently contains low but highly variable amounts of activity. White adipose tissue of guinea pig, rabbit, and rat also consistently contains low and variable amounts of activity, but activity is essentially lacking from white adipose tissue of chicken and pigeon.Unlike gastrointestinal mucosa of rabbit, mucosa of guinea pig and rat contain low and variable activity and activity is essentially absent from mucosa of chicken and pigeon. Significant PEPCK activity is lacking from brain, spleen, lung, and heart tissues of all five species.Rat and bird livers contain essentially only cytoplasmic and mitochondrial PEPCK isozymes respectively, whereas livers of rabbit and guinea pig contain significant amounts of both isozymes. In general, the subcellular distribution of PEPCK activity in the kidney of a given species is the same as in the liver. However, in the chicken, both isozymes are present in the kidney and only the mitochondrial isozyme is present in the liver.Both isozyme activities of PEPCK are present in white adipose tissue and gastrointestinal mucosa of rabbit and guinea pig. Rat adipose tissue contains essentially all cytoplasmic isozyme, and the subcellular distribution of PEPCK activity was not determined in the gastronintestinal mucosa.
Recommended Citation
Wiese, Thomas John, "Species- and tissue-specific distribution of mitochondrial and cytoplasmic isozymes of phosphoenolpyruvate carboxykinase." (1991). Theses and Dissertations. 8720.
https://commons.und.edu/theses/8720